The present invention concerns novel internally or externally applied fluorine containing polymers which impart oil and grease resistance to paper and soil-release properties to textile products. More particularly it concerns copolymerization products of (a) a perfluoroalkyl-substituted (meth)acrylate or (meth)acrylamide, (b) a secondary or, tertiary amino or quaternary ammonium group-containing (meth)acrylate or (meth)acrylamide and (c) vinylidene chloride and, optionally, d) other copolymerizable vinyl monomers, their preparation and use.
The use of perfluoroalkyl-substituted compounds to impart oil and grease repellency to textile and paper substrates is along established practice. For paper treatment the most important products have traditionally been phosphate diesters of a perfluoroalkylalkanol or di-perfluoroalkyl-substituted carboxylic acids, as described in U.S. Pat. Nos. 4,485,251, 4,898,981 and 5,491,261. These compounds are applied either in the wet-endxe2x80x94that is they are added to the pulpxe2x80x94or applied by rollers, a size press or other means to the finished paper as a coating. The fluorochemicals used for treating textiles are all polymers; the vast majority are copolymers of poly-perfluoroalkyl (meth)acrylates. More recently such polymers have also been used as external paper sizes since polymers provide the extra benefit of water resistance which is a desirable feature in many food packaging and fast-food applications.
To achieve water repellency by internal sizing, alkyl-ketene-dimer (AKD; sold under the trade name HERCON by Hercules Inc., among others) is most commonly used since the small amount of fluorine add-on (typically 0.08-0.12%) is inadequate for this purpose. In addition, the commonly used internal fluorochemical oil-sizing agents, even while impart oil sizing, have, due to their inherently surfactant-like xe2x80x9chead-tailxe2x80x9d structure, a deleterious effect on water resistance by inhibiting the AKD curing reaction.
The present invention concerns fluorochemical polymers which are useful as an internally or externally applied oil- and grease proofing paper size which imparts, in addition to oil resistance, excellent water resistance. It has further been discovered that the polymers of the present invention impart excellent soil-release and anti-soiling properties to textiles.
The polymer of the present invention is a copolymer of
a) 45-90% by weight of a perfluoroalkyl-substituted (meth)acrylate or acrylamide,
b) 5-30% by weight of a secondary or tertiary amino or quaternary ammonium group-containing (meth)acrylate or (meth)acrylamide,
c) 1-20% by weight of vinylidene chloride (VDC), and, optionally,
d) 0-10% by weight of a nonfluorinated vinyl monomer.
Relevant prior art includes U.S. Pat. No. 3,919,183 (Jager et al.), which discloses polymers useful as oil repellent coatings for porous substrates such as textile materials and paper which comprise a perfluoroalkylethyl acrylate, optionally copolymerized with up to 95% by weight of other monomers. Among other possible co-monomers, vinylidene chloride and N,N-dialkyl-aminoethyl methacrylate are mentioned. However no vinylidene chloride-containing compositions are exemplified.
U.S. Pat. No. 4,013,627 (Temple) describes textile finishes which are copolymers of 20-99% by weight of a perfluoroalkylethyl acrylate, 1-80% of a vinyl monomer having no non-vinylic fluorine atoms and 0.1-4% of a (meth)acrylate bearing a quarternary ammonium group. Among the possible co-monomers, vinylidene chloride is mentioned but not employed.
U.S. Pat. No. 4,100,340 (Waldmann et al.) describes textile finishes which are copolymers of a perfluoroalkylethyl acrylate, a higher alkyl acrylate, vinylidene chloride and acroylbutylurethane in weight ratios of 1/0.22-0.39/0.45-0.85/0.01-0.14.
U.S. Pat. No. 4,582,882 (Lynn et al.) describes fluorinated paper sizes which are copolymers of 60-80% by weight of a perfluoroalkylalkyl acrylate; 1-30% of a halogenated alkyl or alkoxyalkyl acrylate, 1-15% of glycidyl methacrylate, 1-6% of a (meth)acrylate bearing a quaternary ammonium group and 0-20% vinylidene chloride.
U.S. Pat. No. 4,742,140 (Greenwood et al.) describes copolymers for use on textiles which comprise 40-75% by weight of a perfluoroalkylethyl acrylate, 10-35% of vinylidene chloride and 10-25% of a C2-C18alkyl-(meth)acrylate. An earlier Japanese Patent Application No. 50-54729 (Asahi Glass Co.) discloses similar polymers, but specifies 35-60% of vinylidene chloride and 0.5-5% of N-methylol (meth)acrylamide.
It has now been unexpectedly found that copolymers comprising a perfluoroalkylalkyl (meth)acrylate, a secondary- or tertiary-aminoalkyl(meth)acrylate, vinylidene chloride and up to 10% of copolymerizable nonfluorinated vinyl monomers give superior oil and water resistance to paper products, especially when applied as internal sizes. None of the cited prior art discloses the use of vinylidene chloride and a secondary- or tertiary-aminoalkyl(meth)acrylate as sole comonomers with a perfluoroalkylalkyl (meth)acrylate.
It has further been discovered that the copolymers of the present invention impart excellent soil-release and anti-soiling properties to textile fibers.
The present invention concerns compounds which act either as internally or externally applied oil- and grease proofing paper sizes or as soil-release agents for textile fibers. The preferred compounds are copolymers comprising monomers copolymerized in the following percentages by weight, relative to the total weight of the copolymers:
a) 45-90% by weight of a monomer of formula
RFxe2x80x94Wxe2x80x94Xxe2x80x94C(xe2x95x90O)xe2x80x94C(R1)xe2x95x90CH2 xe2x80x83xe2x80x83(1),
xe2x80x83wherein
RF is a straight or branched-chain perfluoroalkyl group containing 4 to 20 carbon atoms,
R1 is H or CH3,
X is O, S or N(R2), wherein R2 is H or an alkyl group with 1 to 4 carbon atoms,
W is alkylene with 1 to 15 carbon atoms, hydroxyalkylene with 3 to 15 carbon atoms,
xe2x80x94(CnH2n)(O CmH2m)qxe2x80x94, xe2x80x94SO2NR2xe2x80x94(CnH2n)xe2x80x94 or xe2x80x94CONR2xe2x80x94(CnH2n)xe2x80x94, wherein n is 1 to 12, m is 2 to 4,
q is 1 to 10 and R2 is as defined above;
b) 5-30% by weight of a monomer of formula
(R2)2Nxe2x80x94(CH2)kxe2x80x94X1xe2x80x94C(xe2x95x90O)xe2x80x94C(R1)xe2x95x90CH2 xe2x80x83xe2x80x83(2),
xe2x80x83in which the nitrogen atom is partially or completely quaternized or in the form of a salt and X1 is O or N(R2) and wherein
R1 and R2 are defined as above, each R2 is the same or different, and k is 2 to 4;
c) 1-20% by weight of vinylidene chloride, and, optionally,
d) 0-10% by weight of a copolymerizable nonfluorinated vinyl monomer.
Preferably d) is zero.
Especially referred are copolymers in which the monomers are copolymerized in the following percentages by weight, relative to the total weight of the copolymers: a), 70-85% by weight; b), 3-12% by weight; c), 10-20% by weight, and d), zero.
In preferred copolymers, RF is a straight chain perfluoroalkyl group with 6-16 carbon atoms, X and X1 are oxygen and W is an alkylene with 1 to 12 carbon atoms, or X is N(R2), X1 is oxygen and W is xe2x80x94SO2NR2xe2x80x94(CnH2n)xe2x80x94, wherein R2 and n are as defined above.
The most preferred copolymers are those in which RF is a straight chain perfluoroalkyl group with 6 to 16 carbon atoms, R1 is hydrogen, X and X1 are oxygen and W is xe2x80x94CH2CH2xe2x80x94.
A mixture of compounds of the formula (1) with 6 to 16 carbon atoms is advantageously employed to prepare the inventive copolymers. The most especially preferred monomer of the formula (1) to prepare the polymers of this invention is an RF-ethyl acrylate which is available from Clariant Chemical Corp. under the trade name FLOWET AC-812. It has a chain-length distribution of RF-chains of 13xc2x12% C6F13, 48xc2x12% C8F17, 23xc2x12% C10F21 and 1.6% C12F25 or higher.
Preferred compounds of the formula (2) are N,N-dimethylaminoethyl (meth)acrylate; N,N-diethylaminoethyl (meth)acrylate; N,N-dimethylaminopropyl methacrylamide and N-tert. butylaminoethyl methacrylate and their salts.
Useful as co-monomers (d) are a large number of commercially available acrylates and methacrylates, as well as styrene; but preferably methyl methacrylate, N-methylol acrylamide, 2-hydroxyethyl methacrylate, acrylic acid, glycidyl methacrylate and acrylonitrile.
The polymerization of the monomers to form the copolymers of the invention can be carried out as an emulsion or in solution. For emulsion polymerization water-soluble co-solvents are commonly used to aid migration of the otherwise insoluble RF-monomers through the aqueous phase. Useful co-solvents include acetone and methanol. Suitable free radical initiators include water-soluble peroxides or azo compounds, such as potassium persulfate. In another variation of the polymerization in an aqueous medium, the RF-monomer is first emulsified in water using a surfactant and a homogenizer, followed by copolymerization with the other monomers.
The preferred method for making the polymers of this invention however is solution polymerization. Useful solvents are ketones such as acetone, methyl isobutyl ketone and methyl ethyl ketone, esters such as isopropyl acetate, alcohols such as methanol, ethanol and isopropanol, and aromatic hydrocarbons such as toluene.
The polymerization is typically carried out at temperatures of from about 50 to 100xc2x0 C. using a free radical initiator, typically a peroxide or azo compound. Useful initiators include benzoyl peroxide, 1,2-azo-bis-isobutyronitrile (AIBN) and 1,2-azo-bis-(2-methylbutane nitrile) (VAZO-67).
A chain-transfer agent can be present, such as an alkyl thiol, in amounts of from 0.01 to 1 mole percent. After the polymerization is complete, the solution is readily transformed into a cationic aqueous emulsion or solution by first adding an organic acid such as acetic acid and water; then distilling off the solvent.
The copolymers are useful as coatings on porous substrates such as paper and textiles, or on hard substrates such as wood, metal or masonry. In the paper industry, their main usefulness is based on their ability to impart oil and grease resistance to paper which is used for food packaging or for any other type of application where resistance to oily substances is required.
Thus the present invention further relates to a method of imparting oil and grease resistance to paper, which comprises incorporating an amount of a copolymer according to this invention that is effective to impart oil and grease resistance into the paper.
The application of the copolymer to paper can either be to the dry paper through a coating process via a size-press (external paper sizing) or by addition of the copolymer to an aqueous pulp (internal paper sizing). The level of application in either case is preferably in the range of 0.02 to 1% by weight of the copolymer, based on the weight of the dry paper or pulp, corresponding roughly to incorporation of 0.01 to 0.5% by weight of fluorine on the paper or pulp.
The usefulness of the copolymers for treating textile materials lies in their ability to impart soil-release characteristics to a fabric during washing, thus facilitating the removal of stains from tablecloths, pants, shirts, etc., thereby extending their useful life, and to enhance the ability of the treated textile material to shed dry soil. The term soil-release denotes the ease with which a fabric, once stained or soiled, can be washed clean. The anti-soiling effect describes resistance to picking up of dry soil and wet soil (=soil redeposition) by the treated textile material. A soil-release finish is usually a fluorochemical hydrophilic polymer, where the fluorochemical segment provides stain repellency and the hydrophilic segment provides wettability and washability.
Suitable textile materials include cellulosics, especially cotton, polyamides such as nylon, wool and silk, polyesters and polyolefins and blends thereof such as polyester-cotton blends.
Thus the present invention further relates to a method to impart soil-release and anti-soiling characteristics to a textile material, which comprises treating the textile material with an amount of a copolymer according to this invention that is effective to impart soil-release and anti-soiling characteristics thereto.
The preferred amounts of the copolymer to treat the textile material with are the same as for paper or pulp.
The present invention further relates to textile material or paper or pulp which contains 0.02 to 1% by weight of a copolymer according to claim 1 therein.
The following non-limiting examples disclose how to synthesize the inventive copolymers and describe in detail methods of their application to various substrates. They also demonstrate the good performance of the copolymers on the various substrates.